The present invention relates to a machine tool having at least one tool spindle which is displaceable in at least one of three spatial directions in relation to a device for holding workpieces, and in which tool spindle tools for processing the workpieces can be chucked, having a machine magazine in which tools provided for exchange into the at least one tool spindle are kept in store, and having a background magazine in which tools provided for exchange into the machine magazine are kept in store.
The invention further relates to a method for a tool change on a machine tool having at least one tool spindle which is displaceable in at least one of three spatial directions in relation to a device for holding workpieces, and in which tool spindle tools for processing the workpieces can be chucked, having a machine magazine in which tools provided for exchange into the at least one tool spindle are kept in store, and having a background magazine in which tools provided for exchange into the machine magazine are kept in store, in which method the at least one tool spindle is moved into a tool-change position in which tools are exchanged between the machine magazine and the at least one tool spindle, wherein a tool-interchange position is provided at which tools are exchanged between the background magazine and the machine magazine.
A machine tool of this type and a method of the aforementioned type are disclosed in DE 102 25 143 A1.
In the context of the present invention, “a tool spindle which is displaceable in at least one of three spatial directions in relation to a device for holding workpieces” is understood to mean an arrangement in which the tool spindle and the workpiece are displaceable in relation to one another in at least one of the three orthogonal spatial axes x, y and z. When the machine tool is what is referred to as a travelling-column machine, all three directions of movement are implemented in the tool spindle, the latter thus being advanced to the workpiece in the x, y and z directions.
However, it is also possible here to implement one or two directions of movement, i.e. in particular the x and y directions, in the workpiece.
It is, however, irrelevant for the implementation of the present invention how the axes of movement are distributed between the tool spindle and the workpiece.
If all three directions of movement are implemented in the tool spindle, the machine tool is preferably a travelling-column machine having a vertical-axis tool spindle; the tool spindle is thus advanced to the workpiece in the vertical direction. However, it is also possible for the tool spindle to be aligned horizontally, such that advancing takes place horizontally.
It is furthermore possible for further pivot axes or rotation axes to be arranged either in the tool spindle and/or in the workpiece.
Without departing from the scope and the advantages and functionalities of the present invention, the machine tool here may be equipped with one, two, four or even more tool spindles. The plurality of tool spindles are preferably synchronously displaced in relation to one another, they are preferably rigidly coupled to one another and in this event serve for the simultaneous and contour-identical processing of as many workpieces as there are tool spindles.
The present invention starts from a machine tool in which both a machine magazine and a background magazine are provided.
A multiplicity of machine tools having tool magazines are known from the prior art. It is customary for the tool magazine to be attached to the machine tool; it may be configured, for example, as a chain magazine or a disc magazine.
In machine tools of this type, a variety of tools which are successively inserted into the tool spindle are kept ready in order to perform specific processing operations on a workpiece. The tool change between the tool magazine and the tool spindle takes place in this case by a variety of ways and means.
For example, DE 197 24 635 A1 discloses a machine tool having a background magazine in the form of a disc magazine in which a double gripper which conveys tools back and forth between the disc magazine and the working space of the machine tool is provided. The double gripper in this case removes a tool from the disc magazine and is then pivoted together with that tool into the working space. There, by way of the pick-up method, the tool spindle approaches the double gripper, deposits the tool that is currently chucked in the tool spindle into the free gripper of the double gripper and then grips the tool that was previously inserted into the double gripper from the disc magazine.
In addition to the disc magazine, the known machine tool also has a machine magazine which is located on the machine tool and from which tools can be likewise changed into the tool spindle. The tool which has been exchanged from the disc magazine into the tool spindle by means of the double gripper can also be deposited into the machine magazine in this manner with the aid of the tool spindle.
A further machine tool, in which the machine magazine is configured as a chain magazine, is disclosed in DE 190 19 446 A1. To change tools, the chain magazine is pivoted into the working space of the machine tool where a tool change to the tool spindle takes place by way of the pick-up method.
In the machine tools described so far, only a specific number of tools can be stored intermediately in the respective machine magazine, such that it is often necessary for the workpiece to be re-chucked on another machine tool in order to be able to carry out processing operations with further tools here.
In this context, DE 197 24 635 A1 describes a machine tool in which an external tool magazine is provided as a background magazine by way of which further tools are provided.
A similar design is also shown in DE 100 20 801 A1. The background magazine is designed as a rack magazine in which a very large number of tools can be stored intermediately. A transfer device which removes tools from the rack magazine and conveys them to a transfer position which is stationary in relation to the rack magazine is provided on the rack magazine.
This transfer position is also served by a double gripper which is pivotably mounted on the machine frame and which, in the transfer position, can deliver a tool to the transfer device or remove a new tool from the transfer device. Having this new tool, the double gripper then pivots close to the working space of the machine tool where it provides the new tool for a tool change by way of the pick-up method.
Once the tool spindle has terminated a processing operation, it travels to the spindle position of the double gripper and initially deposits the tool which has been employed so far into the free gripper. Thereafter, the tool spindle grips the tool which has been newly brought from the rack magazine and again travels to the working space, where processing of the workpiece continues using the new tool.
In theory, any number of available tools are possible with this design, such that the problem of a limited number of available tools that exists for reasons of space in machine magazines is solved by the background magazine together with the transfer device and the double gripper.
The known construction is, however, complex in its design, the tool change not being sufficiently rapid for many applications.
Proceeding therefrom, DE 102 25 143 A1 discloses a machine tool which combines the principle of the machine magazine which, although having a limited number of stored tools, has the potential for rapid tool changes, with the advantages of the background magazine in which the storage potential for any number of tools can be utilized.
The known machine tool thus enables, on the one hand, a rapid tool change by means of the machine magazine, wherein tools can be removed from the background magazine and new tools can be introduced into the machine magazine, virtually expanding the machine magazine as it were to the size of the background magazine.
In the known machine tool, the machine magazine is configured as a chain magazine which is arranged on the y-slide of the machine tool so as to ride therewith, which machine tool is configured as a travelling-column machine. For a tool change, this chain magazine is displaced into the working space of the machine tool, whereby, for a tool interchange with the background magazine, it has to be moved into a transfer position.
Despite this machine tool meeting many requirements on account of the, in principle, unlimited number of tools and the rapid tool change, it is in the case of many applications still not suited to particularly rapid tool-change times and, in particular, to particularly rapid chip-to-chip times.